NATO members and partners have launched their biggest-ever joint exercise in Poland.

The staging of the Anaconda-16 training exercise on June 6 through June 16 comes at a time when Central and Eastern European countries are seeking stronger security guarantees against an increasingly aggressive Russia.

The exercise involves about 31,000 troops from Poland, the United States, and 17 other NATO member states, as well as from five NATO partner countries.

About 12,000 of the troops are from Poland, almost 14,000 from the United States, and about 1,000 are from Britain.

Russia says any presence of NATO troops close to its borders is a threat to its security and recently warned it will take measures to respond.

Drills also are being staged by NATO forces in the Baltic states.

NATO forces and NATO partner countries on June 3 also began exercises known at BALTOPS 16 in the Baltic Sea region.

Those drills are scheduled through June 18 with about 6,000 troops from 17 countries -- including the United States, Germany, Britain, the Netherlands, Estonia, Latvia, Lithuania, Poland, Denmark, Sweden, and Finland.

Aleksandr Grusho, Russia's permanent representative to NATO, said on June 6 that Moscow will closely analyze the drills in the Baltic region to assess whether they pose any risks to Russia.

The exercises are taking place just weeks before NATO holds a summit in Warsaw that is expected to decide on whether to significantly increase NATO troop and equipment deployments to bases in Poland and the Baltic states.